Roswell is where an American Military base tests it's new aircraft...so a UFO happens to crash just down the road!.....hello! The theory took off in the 1970's due to conspiracy books...a miltary offical claimed it was a UFO, he also claimed he was a decorated WW 2 fighter pilot which was proved un-true and he was a known story teller....but the myth took off as more books came out.
Amityville haunted house - The Lutz family did move out of the house where a family was murdered, probably freaked by the thought. Years later a semi-FICTIONAL book was written claiming pig faced demon attacks and Priests being told to "Get Out"....funny how the demons seemed to move out too...the new owners for the last 30 years only complained about the damn tourists. Lutz made money from his "Amityville" trademark and sued everyone.
A lie told enough times becomes truth....at least to some.